Linear guide for the falling weight of a pile hammer

ABSTRACT

A linear guide for the falling weight ( 1 ) of a pile hammer, having at least one bearing housing ( 4, 24 ) that can be arranged according to the present invention without lubricant in that the bearing housing ( 4, 24 ) has sliding elements ( 5, 25 ) preferably made of plastic and contacting the falling weight ( 1 ) in order to guide the weight, and the sliding elements can be installed and removed while the falling weight ( 1 ) is installed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application No. 102008052724.6, filed Oct. 22, 2008, and International Patent Application No. PCT/EP2009/006712, filed Sep. 17, 2009.

TECHNICAL FIELD OF THE INVENTION

The invention relates to a linear guide for the falling weight of a pile hammer, having at least one bearing housing at least partially enclosing the falling weight.

BACKGROUND OF THE INVENTION

Such pile hammers are used in foundation works for driving piles into the ground, in particular into the bed of a body of water. In this process, a falling weight is periodically lifted and dropped in order to generate ram strokes which drive the pile into the subsoil. The falling weight as such is guided in a linear guide in which it can perform linear up and down movements in the axial direction. The known pile hammers have linear guides made of metal and require lubricants so that the falling weight can be guided in its vertical movement with as little friction and wear as possible. During pile-driving under water, the lubricants can get into the water and contaminate it.

SUMMARY OF THE INVENTION

The object of the invention is to specify a linear guide of the type mentioned above for the falling weight of a pile hammer which operates without a lubricant.

This object is attained according to the present invention in that at least one bearing housing is provided with sliding elements contacting the falling weight in order to guide the weight, and the sliding elements can be installed and removed while the falling weight is installed. A linear guide with sliding elements can be operated without a lubricant, but has to take account of the fact that the sliding elements wear out during long periods of operation, in particular when the sliding elements consist of plastic. If the plastic sliding elements are simply arranged between the falling weight and a bearing housing, the replacement of worn sliding elements by new sliding elements would only be possible with great effort. For this purpose, the falling guide would, in particular, have to be removed from the bearing housing. This is considerably time-consuming and represents an economic disadvantage because the pile hammer is not available for pile-driving while the sliding elements are being replaced. The invention, therefore, provides that the sliding elements can be installed and removed with the falling weight installed. This results in a significant economic advantage because the sliding elements can be replaced much more quickly without removing and installing the falling weight than according to the prior art.

A first embodiment of the invention provides that the bearing housing has several installation openings respectively going from the outer side to the inner side facing the falling weight, the openings being distributed over the circumference thereof, and in each of which a sliding element is arranged, and which can each be closed from the outer side with a supporting element. In order to be installed, the sliding elements are slid through the installation opening until they contact the falling weight. The installation opening is then closed by the supporting element which supports the sliding element from the outer side and presses it onto the falling weight. During operation of the pile hammer, the lateral forces required for guiding the falling weight are transferred to the supporting elements via the sliding elements and thus to the bearing housing.

In a simple arrangement of the first embodiment the circumferential surfaces of the sliding elements and of the installation openings at least have a cylindrical shape in sections, the front of the sliding elements being adjusted to the shape of the circumferential surface of the sliding element. The falling weight usually has a cylindrical shape, i.e. it has a cylindrical circumferential surface. The front of the sliding element then has a complementary shaped sliding surface which contacts the cylindrical circumferential surface of the falling weight in the installed state of the sliding element. The falling weight can thus move unhindered in the vertical direction, constantly being guided by the entire sliding surface of the sliding element.

The invention can, however, also be used if the falling weight has different shapes, for example an oval or square cross-section. In the first case, the sliding surfaces of the sliding elements are given a different curvature which is adapted to the falling weight. In the second case, the sliding surfaces of the sliding elements can be arranged as flat surfaces.

The arrangement of the circumferential surfaces of the sliding elements is advantageously determined by those of the installation openings. As the installation openings can easily be designed as bores, this results in a special advantage for the cylindrical shape of the installation openings and of the circumferential surfaces of the sliding elements.

The invention is further improved in that the supporting elements have a central projection and the sliding elements are provided with a central perforation so that they can be attached to the projection of the supporting elements. In this way, the position of the sliding elements relative to the supporting elements can be fixed such that mounting the sliding elements in a tilted or incorrect position is avoided.

It is especially advantageous if four installation openings distributed over the circumference of the bearing housing are provided for four sliding elements.

An embodiment of the invention is proposed such that the sliding elements or the supporting elements are provided with an elastic compensation element configured transversely to the direction of movement of the falling weight. Small differences in length can be compensated with the compensation element, in particular those occurring due to wear of the sliding elements during operation.

If the sliding elements can be attached to the supporting elements on their side facing the supporting elements, the installation is, on the one hand, facilitated because an attached sliding element cannot inadvertently drop, and, on the other hand, the position of the sliding elements relative to the supporting elements is fixed, in particular with respect to the rotation about an axis arranged transversely to the direction of movement of the falling weight. When installing the unit consisting of the sliding element and supporting element only the correct position of the supporting elements has thus to be taken into account. The sliding elements are then automatically located in their correct installation position.

In a further development of this feature, the sliding elements are provided with screw threads on their side facing the supporting elements and/or the supporting elements have bores for the passage of attachment screws, at least one sealing element to prevent water from penetrating being preferably provided between at least one sliding element and the associated supporting element. By means of these features, the sliding elements can be tightly screwed to the supporting elements in their correct installation position. When used under water, the sealing element, which can, for example, be configured as an O-ring, prevents water from penetrating into the linear guide according to the present invention. Leakage of, for example, lubricant from inside the linear guide into the body of water, is also prevented. An alternative version of the embodiment, in which the sliding elements are provided with cylindrical projections on their side facing the supporting element, and the supporting elements have bores for accommodating the cylindrical projections, the cylindrical projections having threads for screwing in attachment screws, also serves the same purpose.

The feature that the supporting elements have bores arranged radially outside the sliding elements for the passage of attachment screws, which can be screwed into associated threads on the bearing housing, serves the fixation of the supporting elements with respect to the bearing housing, in particular also for the fixation in the rotational direction according to both last mentioned versions of the embodiment, and thus, finally, for the fixation of the correct installation position of the sliding elements with respect to the bearing housing and to the falling weight.

A second exemplary embodiment of the invention provides that the bearing housing has at least one installation opening that is accessible from its outer side and that can preferably be closed, through which a ribbon-shaped sliding element can be inserted tangentially to the falling weight, the bearing housing being preferably provided on its inner side with a groove following the circumference of the falling weight for accommodating the ribbon-shaped sliding element. The ribbon-shaped sliding element is guided through the groove such that a worn sliding element can, for example, be pulled out through the installation opening, and a new sliding element can be inserted tangentially to the guiding element. On the other hand, the groove prevents the displacement of the ribbon-shaped sliding element in the direction of movement of the falling weight. An advantage of this form of arrangement with ribbon-shaped sliding elements is that the sliding element encloses at least a large part of the circumference of the falling weight and thus guides it over a very large area.

An arrangement of this second exemplary embodiment of the invention provides that the ribbon-shaped sliding element consists of interconnected sliding elements. The sliding elements as such are sufficiently rigid to resist the large forces required for guiding the falling weight, whereas the mobility required for inserting the ribbon-shaped sliding element through the installation opening is ensured by the interconnection of the sliding elements.

In a further arrangement of this embodiment, the sliding elements have protruding moldings on one side and indentations on the opposite side which are intended for accommodating the protruding moldings of an adjacent sliding element such that an interlocking connection is possible.

The sliding elements preferably consist of a polymer material and are produced by means of injection molding. If necessary, two or more types of sliding elements consisting of two or more different materials can, however, be combined in order to improve the function of the sliding element. The sliding element then consists of sections periodically arranged one behind the other, which are formed by two or more different types of sliding elements.

In a preferred embodiment the bearing housing has two opposite installation openings through with a ribbon-shaped sliding element can be inserted. Each ribbon-shaped sliding element thus just encloses half of the circumference of the falling weight. The cost of two ribbon-shaped sliding elements is relatively low. The cost would only be smaller if a single ribbon-shaped sliding element were arranged. It would then, however, have to enclose the falling weight over a circumferential area of more than 280° in order to achieve similar good results in guiding the falling weight. Such a sliding element would, therefore, be very long and the insertion particularly difficult during installation.

As a result of the feature that the installation openings can each be closed by means of a cover, which can preferably be attached to the bearing housing by means of screws, the ribbon-shaped sliding element is prevented from sliding out and in addition, dirt is prevented from penetrating into the inner space.

Two exemplary embodiments of the invention will hereafter be explained in more detail with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 shows a guide tube with two bearing housings of the linear guide according to the present invention a) in a top view and b) in a cut view;

FIG. 2 shows a perspective view of the bearing housing in a first embodiment with removed sliding elements;

FIG. 3 shows the same bearing housing as in FIG. 2, but in a top view;

FIG. 4 shows a perspective view of the same bearing housing with installed sliding elements;

FIG. 5 shows a top view of a falling weight with contacting sliding elements without bearing housing;

FIG. 6 shows a bearing housing in a second embodiment of the invention a) in a perspective view and b) in a cut view;

FIG. 7 shows a perspective view of a sliding element of a ribbon-shaped sliding element; and

FIG. 8 shows a perspective view of the ribbon-shaped sliding element according to the second embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

A falling weight 1 is apparent from FIG. 1, which is guided movably in the vertical direction 2 inside a guide tube 3. The guide tube 3 is provided with two bearing housings 4, each enclosing the guide tube 3, and whose sections 3 a, 3 b, 3 c jointly connect to the guide tube 3. The connection of sections 3 a, 3 b, 3 c to one another is carried out via flanges at the bearing housings 4 which are, in particular, apparent from FIG. 2. As is best apparent from FIGS. 2 to 4, the bearing housing 4 is provided with sliding elements 5 made of plastic which, in the installed state, are arranged on the inner side of four installation openings 6. The four installation openings 6 are arranged distributed in opposite pairs and spaced apart by 90° each over the circumference of the bearing housing 4. In the installed state (FIG. 4), the four sliding elements 5 are fixed in the four installation openings 6 by means of four supporting elements 7.

The sliding elements 5 have a cylindrical circumferential surface 8 which is accommodated and supported in a cylindrical inner surface 9 of the installation openings 6 arranged in a complementary manner. The front of the sliding elements 5 is arranged as a sliding surface 10 and adjusted for contacting a circumferential surface 11 of the falling weight 1. As is best apparent from FIG. 5, the circumferential surface 11 of the falling weight 1 is a cylindrical surface and the sliding surface 10 of the sliding elements 5 is shaped in a complementary manner such that the sliding elements 5 substantially contact the circumferential surface 11 of the falling weight 1 with all its sliding surface 10 and securely guide the falling weight 1 in its movement in the vertical direction 2.

As is best apparent from FIG. 3, each of the supporting elements 7 has a central projection 12. As is best apparent from FIGS. 2 and 4, each of the sliding elements 5 has a central perforation 13 by means of which they can be attached to the projection 12 of the supporting elements 7. Furthermore, each of the sliding elements 5 has four cylindrical projections 14 on their side facing the supporting element 7 which are used for attaching the sliding elements 5 to the supporting element 7.

For this purpose, the supporting elements 7 are provided with four bores 15 which are used for accommodating the cylindrical projections 14 of the sliding elements 5. The cylindrical projections 14 have threads for respectively screwing in four attachment screws 16 from the outer side of the supporting elements 7. When using the linear guide according to the present invention under water, the system can be provided with a seal, by means of an O-ring, for example. The supporting elements 7 as such have a circumferential flange 17 protruding outward which is provided with eight bores 18 for the passage of eight screws 19. As is best apparent from FIG. 2, the screws 19 can respectively be screwed into eight tapped holes 20 on the bearing housing 4, the supporting elements 7 being attached to the bearing housing 4.

A second exemplary embodiment of the invention is shown in FIGS. 6 to 8.

The bearing housing 24 has two installation openings 26 that are accessible from its outer side 21, through which a ribbon-shaped sliding element 25, as it is shown in FIG. 6, can be inserted tangentially to the falling weight 1. The falling weight 1 has not been drawn in FIG. 6 for the sake of clarity.

On its inner side 22 the bearing housing 24 has a groove 23 that follows the circumference of the falling guide 1, which is not shown, that receives the ribbon-shaped sliding element 25.

After inserting the ribbon-shaped sliding element 25, the installation opening 26 is closed by means of a cover 27. FIG. 6 shows one of the installation openings without the cover 27 and an installation opening 26 closed by means of the cover 27. After removing the second cover 27, a second sliding element 25 can obviously be inserted into the second installation opening 26 such that the falling weight 1, which is not shown, is enclosed over the major part of its circumference by both sliding elements. Both covers 27 are attached with screws 37 to the bearing housing 24. For this purpose, the bearing housing is provided with eight tapped holes 33 for screwing in the screws 32.

FIG. 8 shows the design of the ribbon-shaped sliding element 25 with a plurality of sliding links 28. All the sliding links 28 together form a sliding surface 13 on the side facing the falling weight 1 for guiding the falling weight 1. As is best apparent from FIG. 7, each of the individual sliding links 28 has two protruding moldings 29 which each engage in an interlocking manner with two indentations 31 of each of the adjacent sliding elements, as a result of which the interconnection of the sliding links 28 is ensured.

The sliding links 28 can, for example, be made of plastic by means of injection molding. A variety of polymer materials is suitable for this purpose.

Depending on the requirements, several materials can, however, also be combined. In this case, there will then be two or more types of sliding links 28 made of two or more different materials. The ribbon-shaped sliding elements 25 will then consist of sections periodically arranged one behind the other, each section consisting of two or more different types of sliding links 28.

The foregoing description of various embodiments of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise embodiments disclosed. Numerous modifications or variations are possible in light of the above teachings. The embodiments discussed were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled. 

1.-17. (canceled)
 18. A linear guide for a falling weight of a pile hammer, comprising at least one bearing housing at least partially enclosing the falling weight, the at least one bearing housing having sliding elements contacting the falling weight configured to guide the weight, the sliding elements being removable and installable without removing the falling weight from the bearing housing.
 19. The linear guide according to claim 18, the sliding elements being made of plastic.
 20. The linear guide according to claim 18, the bearing housing having an outer side and an inner side and several installation openings going from the outer side to the inner side facing the falling weight, the openings being distributed over the circumference of the bearing housing with a sliding element being arranged in each of the installation openings, each installation opening being configured to be closed with a supporting element.
 21. The linear guide according to claim 20, the falling weight being of substantially cylindrical shape, the sliding elements having circumferential surfaces with at least portions of cylindrical shape, the installation openings having inner surfaces with at least portions of cylindrical shape, and each of the sliding elements having a front forming a sliding surface adjusted to the cylindrical shape of of the falling weight.
 22. The linear guide according to claim 20, the supporting elements each having a central projection, and the sliding elements each having a central perforation configured to receive the projection of one of the supporting elements.
 23. The linear guide according to claim 20, comprising four of the installation openings distributed over the circumference of the bearing housing for four of the sliding elements.
 24. The linear guide according to claim 20, further comprising compensation elements attached to the sliding elements or the supporting elements, the elastic compensation elements acting in a horizontal direction.
 25. The linear guide according to claim 20, the sliding elements being configured to be attached to the supporting elements.
 26. The linear guide according to claim 25, each sliding element having threaded holes on the side facing one of the supporting elements and each supporting element having corresponding bores for attachment screws, at least one sealing element being arranged between at least one of the sliding elements and the respective supporting element.
 27. The linear guide according to claim 25, each sliding element having cylindrical projections on the side facing the supporting element, the supporting elements having bores for accommodating the cylindrical projections, and at least one of the cylindrical projections having a threaded hole for screwing in an attachment screw.
 28. The linear guide according to claims 20, the supporting elements having bores radially arranged outside the sliding elements for the passage of screws which are screwed into associated threads on the bearing housing.
 29. The linear guide according to claim 18, the bearing housing having an outer side with at least one closable installation opening accessible from the outer side, the at least one installation opening being configured for inserting a ribbon-shaped sliding element tangentially to the falling weight, the bearing housing further having an inner side with a groove along the circumference of the falling weight for accommodating the ribbon-shaped sliding element.
 30. The linear guide according to claim 29, the ribbon-shaped sliding element consisting of interconnected sliding links.
 31. The linear guide according to claim 30, the sliding links having protruding moldings on one side and indentations on the opposite side which are intended for accommodating the moldings of an adjacent sliding element for connecting the sliding elements in an interlocking manner.
 32. The linear guide according to claim 30, the sliding elements consisting of a polymer material and manufactured by injection molding.
 33. The linear guide according to claim 30, the sliding element having two or more types of sliding links consisting of two or more different materials and that the ribbon-shaped sliding elements consist of sections, each section consisting of the two or more different types of sliding links, the sections being arranged to form a periodical arrangement of the two or more different types of sliding links.
 34. The linear guide according to claim 29, the bearing housing comprising two opposite installation openings.
 35. The linear guide according to claim 29, each of the installation openings being configured to be closed by a cover attachable to the bearing housing with screws. 